Furnace-hoist.



D. LARSON.

FURNACE HOIST.

APPLICATION FILED MAR. 21, 1913 Patented Feb. 2, 1915.

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MLW LM D. LARSON.

FURNACE HOIST.

APPLICATION FILED MAR. 21, 1913.

1,127,364. Patentd Feb. 2, 1915 2 man's-SHEET 2.

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DAVID LARSON, OF BERLIN, GERMANY, ASSIGNOR T0 OTIS ELEVATOR COMPANY, OF JERSEY CITY. NEW JERSEY; A CORPORATION OF NEW JERSEY.

FURNACE-H0181.

Application filed March 21.

To all whom it may concern Be it known that I, DAVID Laasox, a subject of the King of Sweden, residing in Berlin, Germany, have invented a new and use ful Improvement in Furnace- Hoists, of which the following is a specification.

My invention relates to a system of electric control for hoists, and more particularly to an automatic push button or remote control system for a skip hoist such as is used in charging a blast furnace.

An object of the invention is the proyision of a system of electric control in which the initial operation of starting the hoist is effected by a push button or other circuit closin device, whereupon the motor will automatically start and accelerate to fullspeed until the upper limit of travel is reached when the hoist will automatically slow down and stop with the load directly over the charging bell. After a predetermined length of time. the motor will automatically reverse and return the empty skip to the lower landing thereby completing one cycle of opera tion.

Another object of the invention is the pro vision of means for stopping the hoist at any point in its travel for both an ascending and descending lowland for insuring that the load will again he started and accelerated in the same direction of travel as before it was stopped, thereby preventing the operator from making mistakes in regard to the direction the hoist ought to run after having been stopped.

Other objects of the invention will appear hereinafter. the novel combinations of elements being pointed out in the appended claims.

1n the accoin mnying drawings, Figure 1 represents a single skip furnace hoist containing an embodiment of my invention; Fig. 2 is a wiring plan or diagram of electrical circuits by means of which I carry out my invention.

'Like characters of reference denote similar parts in both figures.

In Fig. 1, a load carrying device or bucket B is suspended from a carriage C which is adapted to travel up. and-down the'incline RI The bucket B may be loaded with ore, coke,

limestone-etc at the lower horizontal portion of the incline and raised by means of an electric motor M, and cables S to a position directly over the mouth of a blast fur- Specification of Letters Patent.

PatentedFeb. 2, 1915.

1913. Serial No. 755,902.

.be of any desired character best suited for the purpose of transporting a load of material for charging the furnace. A power house D may be located at any convenient place but is preferably situated at the bottom of the incline and contains the motor M. controller K, stop motion switch A, and the operating push button P, together with an emergency and stop switch.

The system of electrical circuits used in carrying out my invention and illustrated in Fig. 2 will next be considered, the parts being in a position corresponding with the skip at the furnace mouth and the emergency switch in operated or open position.

Referring to Fig. 2, I will first point out the various controlling devices and their functions and thereafter describe the various electrical circuits and the resrllts attained therefrom. A potential switch 1 is normally in closed position and may be opened to cut off the current supply to the system by means of any one of a'number of safety or emergency devices comprising a safety switch 2,' overload circuit breaker 3. slack cable switch 4, upper and. lower limit switches 5 and 6, anda governor switch 7, the latter being connected in the usual way to run with the hoisting machine or other rotary part of the apparatus. An accelerating magnet 8 and load magnets 10 control a resistance 9 in the motor circuit. An auxiliary brake relay 11 operates to prevent the release of the brake B unless the armature circuit is completed. Stopping magnets are shown at 12 and 13v and they control a resistance 22, a down magnet 16 is controlled by an adjustable dashp0t'23 which retards its movement toward closed position after the load has stopped at the uppenlimit over the furnace. A direction magnet 17 coning a shunt field. 14 and seriesfield 15.

' In order to place the system in condition for operation, the safety switch 2 is first closed and the potential switch 1 also closed, the circuit for the retaining magnet of the latter switch including not only the emergency switch 2 but the normally closed contacts of the governor, limit and slack'cable switches 7, 6, 5 and 4, respectively. A circuit is now closed to the magnet winding of the down relay 16 from the-lmain, by way of'the conductor 21, lower contacts 26 of the direction magnet 17, winding of relay 16, and by the conductor 25, and contacts 24 of the potential switch to the main The dashpot 23 associated with the core of the dowr. relay 16 will retard the action of the -latter so that the closing of the relay contacts will take an appreciable length of time which may be lengthened or shortened at will by suitably regulating the dashpot, it being understood thatthe time required to close the relay contacts represents the time that the load is normally held stationary over the mouth of the furnace, or in other words, during the dumping period. As soon as these contacts come together a circuit is closed to the operating magnet of the down reversingswitch 20. This circuit may be traced as follows: from the+ main by way of the conductor 21, lower contacts 26 of direction relay 17, contacts of down relay 16, wire 27 contacts .of automatic stop motion switch 28, wire 29, magnet winding of the'down reversing switch. wire 30, right hand contacts of stop switch 18. wire 31,

' contacts of stop motion switch 70, and by wire 25 to the main by Way of the potential switch contacts 24. The down reversing switch is now energized to raise its contacts and thereby establish a circuit to the motor to cause-it to lower the empty bucket. The motor circuit may be traced from the main, through the contacts 34 of reversing switch 20, wire 35, brush 36, the armature of the motor, bruslr37, winding of relay 11, Wire 38, reversing switch contacts 39, re-

sistance 9, series field 15. wire 40, winding of overload relay 3 and through the potential'switch contacts to the main'. A

local circuit'in shunt to the armature of the motor is also closed at this time, said circuit being traced from the armature brush 37. winding of the relay 11, wire 38, contacts of relay 42, wire 43, a small portion of the resistance 22, and by wire 44 to the brush 36. The closing of the reversing switch 20 establishes a circuit to the brake 'B, which circuit may be traced from the main by wire 21, contacts 45 of reversing switch 20, wire46, magnet winding of the brake B, brake resistance 47, wire 48, contacts 49 of reversing switch 20, wire 25, and by the potential switch contacts 24 to the main. The resistance-47 in the brake circuit tends to prevent the brake from releasing but since the relay 11 is connected in the motor armature circuit this relay will operate and close the contacts 50 which short circuit or by pass the brake resistance 47 and permit the brake to receive cur ent at the full line potential, whereupon it will release the brake shoe and permit the motor to rotate. As soon as the brake is released, the brake contacts 51 will open, thereby again insert ing the resistance 47 in the brake circuit to .prevent'overheating of the brake magnet winding. The motor will now start to 'lower the bucket at slow speed, the resistance 9 being in series with the motor armature and a small portion of the resistance 22 being in parallel to the armature. As soon as the motor circuit was completed at the contacts of the reversing switch 20, the auX-' iliary accelerating relay 52 received current, thereby closing its contacts 53 and connect ing the winding of the accelerating magnet 8 across the motor armature.

The circuit of the auxiliary accelerating relay 52 may be traced from the main by way of wire 21, contacts 26 of the direction magnet 17, contacts of down magnet 16, wire 27, contacts of stop motion switch 54, wire 55, contacts 56 of relay 57, wire 58, magnet winding of relay 52, wire 59, contacts 49 of the reversing switch 20, and by wire 25 to the main. The load magnets 10 receive 'current from the main by way of wire 21., back contacts of the stopping magnet 13, load magnet windings in parallel, wire 48, contacts 49 of switch 20, and by wire 25 to the main. Th load magnets 10 will now operate to close by short circuit a portion of the starting re-. sistance 9. Since the right hand load magnet contains a resistance in series with its winding,,it will not operate as soon as its companion magnet and therefore the first two portions of the starting resistance will he cut out or short circuited successively. This results in permitting the motor to run at slightly increased speed. The auxiliary stop magnet 41 also operates upon the 010- sure of the reversing switch 20, its 'ma net winding being connected across the con uctors 55 and/48, which are connected respectively to and After the bucket has beenlowered through a short distance the con-. tacts of stop motion switch 60 close and estabeir contacts and thereiso lish a circuit to the magnet winding of the auxiliary stop magnet 42. This circuit may be traced from the positive wire 21, contacts of stop motion switch 60, contacts of stop motion switch 63, wire 61, Winding of magnet 42, contacts 62, and by wire 48, reversing switch contacts 49, and wire 25 to the main. The auxiliary stop magnet 42 now opens the contacts 64, thereby opening the circuit in parallel to the motor armature through the resistance 22. This operation efl'ects a further increase in motor speed, and as the counter-electro-motive force of the armature rises the accelerating magnet 8 is enabled successively to close its contacts, thereby short circuiting the entire starting resistance 9. As the last or right hand contacts of the accelerating magnet close, the auxiliary contacts associatedtherewith short circuit the small resistance 64 in series with the magnet winding of the relay or final accelerating magnet 57 and the latter closes its upper contacts, thereby short circuiting the series field 15 and open circuiting the auxiliary eccelerating magnet 52 at the contacts 56. The magnet 52 is now denergized and opens its contacts 53, thereby open circuitin'g the winding of the accelerating magnet 8 and the accelerating magnet contacts at once move to open posltion. The resistance 9, however, is not reinserted in the armature circuit at this time, since the final acceler' ating magnet '57 remains energized, and keeps the entire starting resistance as well as the series field winding of the motor shortcircuited. By this time, the motor has antomatically run up to full speed, operating as a pure shunt motor. The resistance 64 is once more placed in series with the winding of the magnetof final accelerating magnet 57, so as to keep it cool, and, since the circuit through the accelerating magnet 8 is open, the latter will remain cool, and its resistance will not vary so that it will act uniformly when again called into use, which would not be the case were it to remain energized, as the heating action of the current would tend to increase its ohmic resistance andhence the contacts controlled by the accelerating magnet would not respond to the same counter-electro-motive force as they did before when again called into use, which is obviously undesirable.

The motor lowers the bucket 0' skip at full normal speed until the same a -proaches within a predetermined distance of the lower landing, say for instance 25. feet. At this time the stop motion switch54 operates to open its contacts, thereby interrupting a circuit through the windings of the auxiliary stop magnet 41 and final accelerating mag net 57 I This operation reinserts the greater part of the starting resistance 9 into the motor armature circuit and places the stopping resistance 22 across or in shunt to the armature which immediately efieots a slow down of the motor. As the skip apthe lower terminal at reduce ,d, the con tacts of stop motion S'Wltu. 37 close and thereby connect the stopping magnet 13 across the motor armature and the same will operate more or. less of its contacts decreas ing the stopping resistance 22 'in parallel t the motor in proportion to its load and speed. will be opened before the motor h celerated to full speed in a downwazc rection, so that the stop magnet, even though its circuit is complete, will not have sufii cient energization to operate before these con tacts on the stop motion switch are m ved to open position.

The operation of the contacts of the stopping magnet interrupts the circuit to the load magnets 10 and they become denergized and open their contacts to insert more of the starting resistance 9 into the armature circuit. This operation brings the motor and skip to a very slow speed. Just before the skip reaches the lower landing, the auxiliary stop magnet 42 is open circuited at the contacts of stop motion switch 63, which short circuits practically all or at least the greater part of the resistance 22, and the motor speed is still further reduced. As the skip reaches the lower, landing, the circuit to the reversing switclnQO is interrupted at the contacts of the stop motion switch 28 and all current supply is at once cut oil fromthe. motor and the brake is applied.

In order to start the skip in an upward direction, all that the operator has to do is momentarily to press the starting push button I. A circuit is thereby established to the magnet winding of the direction magnet 17 which circuit may be traced from the main. wire 21, push button 1, wire 6?, contacts 66 of reversing switch 19, magnet winding of the direction magnet or relay 17. wire 69, contacts of stop motion switch 32. and by way of the wire 25 to the main. The direction magnet now operates and closes its upper contacts which establishes a The contacts of stop motion switch The at the same time opened, thereby preventing the closure of a circuit to the down magnet 16. A circuit to the up reversing switch is closed by the operation of the upper. contacts of the direction magnet 17 and this circuit may be traced as follows: from the main, by way of wire 21, upper contacts of direction magnet. win. 71, contacts of stop motion switch 72 \l'l'Y-lCll are at this time in closed position, Wll 7;}. back contacts 74 of reversing switch 20. magnet winding of reversing switch 19, wire 75, left hand contacts of switch 18, and by wire 69. contacts of stop motion switch 32 through the wire 25 to the main. The reversing switch 19' now operates to connect the motor to the main line in a direction such that the motor will operate to raise the skip. The acceleration of the m0- tor to full speed is effected automatically as before pointed out in connection with a downward operation of the skip. As the latter approaches the upper limit of travel the motor is automatically slowed down and finally stopped. with the load orskip directly over the mouth of the furnace; the process of deceleration being effected automatically and in accordance with the load just as described before in connection with a descending skip. The automatic stop motion switch A will in every instance open or close its contacts at the required time, the cams thereon being individually adjustable so as to bring about the desired connections.

In order to provide against a false operation the reversing switches are electrically interlocked so that it becomes impossib e to move both switches simultaneously to closed position. Should the operator Wish to stop the skip at an intermediate point on the incline, he may do so by opening the stop.

switch 18. When the stop switch is again closed the skip will start again automatically in the same direction it was going before the stop switch was opened. Should the operator desire to go half way, stop, and come down again, or down, stop, and come up again, he may do so by opening first the stop switch 18, and then the safety switch 2, and then close both safety and stop switches and immediately after press the up button P, ifhe desires to go up. To go down he need,

only close the. safety and stop switch. The overload magnet or relay 3 operates to open the potential switch in case of excessive current flow, while the relay 11 in series with the motor armature-prevents the brake from being released in case the armature circuit is open. connected across the main line as shown, or if desired, its circuit may be opened or a resistance introduced therein in order to economize current when themotor is at rest, but I prefer to maintain the shunt field at least partially energized at all times, so as to'insure a substantially dynamic brake action in slowing down and stopping. The magnet windings of several of the switches are arranged so that a resistance will be inserted in their circuits after they have done their work, so as to keep their'windings cool and economize current while the auxiliary stopping relay 41 has a high resistance in parallel to its magnet winding so as to make its action sluggish under certain conditions.

While I have shown my invention applied to a. single skip or blast furnace hoist, it is obvious that the invention is applicable to hoists of alljdescriptions in whlch it is desirable to carry out the idea of automatic op- The shunt field may be permanently eration to its fullest extent. The operation of a hoist containing an embodiment of my invention is absolutely fool proof, and does not require a skilled attendant. The mere pushing of.a button effects a complete cycle of operation and the apparatus is'fully pro tected against a false operation of any character.

Obviously various changes could be made in certain parts of the apparatus by one skilled in the art without departing from the spirit and scope of the-invention, and for this reason I desire not to be limited to the precise arrangement and construction of parts as disclosed.

What I claim and desire to have protected by Letters Patent of the United States is 1. In a system of motor control, the combination of a manual switch for effecting the starting of the motor in one direction, and automatic means having a time constant and controlled by the motor for effect ing a reversal of the motor.

.2. In a system of motor control, the combination of a manual switch for effecting the starting of the motor in one direction, and automatic means having a time constant for. efl'ecting a reversal of the motor after the latter has made a. predetermined number of revolutions. i

3. In a system of motor control, the combination of a'manual-switch for effecting "the starting of the motor in one direction,

and automatically operated means having a time constant for effecting a reversalof the motor.

4. In a system of motor control, the combination of a manual switch for effecting the starting of the motor in one direction, and automatically operated means controlled by a dashpot for effecting a reversal of the motor. T

5. In a system of motor control, the combination of a manual switch for effecting the starting of the motor in one direction, automatic means for effecting the acceleration, slowing down, andistopping of the motor, and an electro-responsive device controlled by the said automatic means for effecting a reversal'of the motor.

6. In a: system-of motor control, the combination of a manual switch for effecting the starting of the motor in one direction, automatic means for effecting the acceleration, slowing down, and stopping of the motor, an electro-responsive device controlled by the said automatic means, and means for controlling the said electro-responsive device. r

7. In a system of motor control, the com- 12 bination'of a manualswitch for effecting the startingof the. m'otorin'one direction, automatic-means forjeffecting the acceleration, slowing'down-and' stopping of the motor, an electroresponsive device controlled by the said automatic means, and a retarding device associated with the said electro-responsive device.

8. In a system of motor control, the combination of a manual switch for effecting the starting of the motor in one direction. auto matic means for effecting the acceleration,

. slowing down and stopping of the motor, an

electro-respons-ive device controlled by the said automatic means. a retarding device associated with the said electro-responsive device, and means for regulating the action of the said retarding device.

9. In a system of motor control, the com-- bination of a manual switch for effecting the starting of the motor in one direction, auto matic means for controlling the acceleration, slowing down and stopping of the motor, and an automatically operated and retarded device for effecting a time interval between the stopping and reversal of the motor.

10. In a blast furnace hoist or skip, the combination of an electric motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing a circuit to said controlling mechanism to effect the operation of the motor in one direction, and automatic means having a time constantfor effecting a reversal of the said motor.

11. In a blast furnace hoist 01 skip, the combination of an electric motor, a load carrying. device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closmg a circuit to said controlling mechanism to effect the operation of the motor in one direction, and means controlled by the motor and having a time constant for effecting a reversal of the said motor.

12. In a blast furnace hoist or skip, the combination of an electric motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing av circuit to said controlling mechauism to effect the operation of the motor in one direction, means actuated by the m0- tor for effecting a stop and reversal of the said motor. and means for introducing a time element between the stop and reversal of the motor.

13. In a blast furnace hoist or skip, the combination of an electric motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing a circuit to said controlling mdchanism to effect the operation of the motor in one direction, means operating in synchromsm with the motor for effecting a stop and reversal of the said motor, and means for introducmg a time element between the stop and reversal of the motor.

1a. In a. blast furnace hoist or skip, the combination of an elcctric'motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing a circuit to said controlling mechanism to effect the operation of the motor in one di rcction. and automatic means for stopping the load carrying device at a predetermined point in its travel and for again starting the said device in a reverse direction after a predetermined lapse of time.

15. In a blast furnace hoist or skip, the combination of an electric motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing a circuit to said controlling mechanism to effect the operation of the motor in one direction. and automatic means for stopping the motor and again starting the same ina reverse direction after a predetermined lapse of time.

16. In a blast furnace hoist. or skip, the combination of an electric motor, a load carrying device connected therewith, circuits for the motor, circuit controlling mechanism, a manually operated device for closing a circuit to said controlling mechanism to v effect the operation. of the motor in one direction, automatic means for stopping and reversing the said load-carrying device, means for introducing a time element between said stopping and reversing, and manually controlled means for stopping the device and again starting the same in either direction of travel.

ii". In a blast furnace hoist or skip, the combination of an electric hoisting motor and a connected load carrying device, re-

versing switches for the motor, an electroresponsivc device or direction relay adapted to effect the operation of the reversing switches, a push button for controlling said clectro-responsive device in one direction,

and automatic means for effecting the optor for effecting the operation of said device in the other direction to effect the reversal of the motor.

19. In a blast furnace hoist or skip, the combination of an electric hoisting motor and a connected load carrying device, re-

versing switches for the motor, an electroresponsive device or directionrelay adapted to effect the operation of the reversing switches, a push button for controlling said -electroresponsive device in one direction, au-

and a connected load carrying device, re-

versing switches for the motor, an electroresponsive device or direction relay adapted to effect the operation of the reversing. switches, a push button for controlling said" electroresponsive device in one direction, in-

tomatic means for effecting the operation of said device in the other direction to reverse the motor, and retarding mechanism for termined lapse of time.

, 21-. In a skip hoist, the combination of a hoisting motor and its connected load carrying device, a push button for starting the reventin said reversal until after a redecame:- of this patent may be obtained for k wi motor in one direction, and automatic means for controlling the motor to move the load carrying device to the top of the incline, hold the same stationary for a predetermined period of time, and then move the said load carrying device to the bottom of the incline and bring the same to rest.

22. In a skip hoist, the combination of a hoisting motor and its connected load carrying device, of a system of control for the said motor for automatically causing the same to move the load carrying device from the bottom to the top of the hoist and eifect the reversalof the motor to lower the said device to the bottom of the hoist and a push 'button adapted-momentarily to close a circuit to the said system of control.

- In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

DAVID LARSON. Witnesses:

HENRY HASPER, .WOLDEMAR HAUPT.

flve cents each, by addressing the Commissioner 0! Patents,

Washington, D. O." 

